Why is my picture blurry?

You have not focused properly.Solution: select ONE focus point; focus; hold it; and only then shoot.

You are using a shallow depth of field. At f/1.4, it is hard to focus.

Subject:

Your subject is moving fast. Solution: pan with the subject or increase ISO, open aperture, or shoot the subject at the apex of its jump, say.

Shutter speed:

You are using a slow shutter speed (slower than twice the lens length, say, so on a 100mm lens you are using a shutter speed slower than 1/200th second). Solution: open the aperture or increase the ISO).

You are using a long lens (say a 300mm lens). On that lens, fast enough shutter speeds are hard to obtain). Solution: Zoom out, increase ISO, open the aperture, or use a tripod.

You are not using a tripod when you ought to. Solution? use a tripod!

You are using a slow lens. An f/3.5-5.6 consumer lens will never do as well as an f/2.8 pro lens. Solution: need I say?

You are using a small aperture, like f/8, when you should be using f/2.8. Solution: open your aperture.

Miscellaneous technique:

Your subject is in the dark – where it is muddy and blurry. Solution: Light your subject well.

You are not using flash when you should be. Solution: need I say?

You are not using IS/VR. These are great features: stabilized lenses are superb and give you several stops. Solution: get an IS/VR lens.

Equipment:

Your camera is faulty – this is very unlikely, but have it checked out.

Your lens is faulty – this is also rather very unlikely, but have it checked out.

Clear? (Pun intended). Try all these and you will see your images improve amazingly. Yes, I know, there are a lot of them. Yes, it’s complicated. But yes… you will take brilliant images once you get all of these right.

I use this as well, but I find that using auto focus point and waiting for it to focus on what I want is still sharper than using single focus point. I can’t understand this. I have a NIKON d7k with 18-105 lens.